In explaining to an alleged date-rape victim why he wasn’t pressing charges in her case, Weld County District Attorney Ken Buck told the woman that her prior relations with the alleged attacker could be used against her if she pursued the matter.

The conversation the Republican Senate nominee had in 2005 with a then-21-year-old University of Northern Colorado student surfaced this week through an audio recording the victim made without Buck’s consent that was released by the liberal group ProgressNow.

In that recording, Buck said he thought her case — she alleged she was raped by an ex-boyfriend whom she invited over when she was drunk — would be tough to prove.

Buck can be heard telling the victim that if she tried to compel him to prosecute, her alleged perpetrator’s lawyer could bring up “possible motives” for her filing the charges to begin with — including the fact she says she had a miscarriage while pregnant with his child more than a year before the incident occurred.

Buck later told The Greeley Tribune that a jury could see it as a case of “buyer’s remorse.”

Buck’s campaign swatted away release of the audiotape as “disgusting” and politically motivated.

“The fact that these Democrat groups are trying to smear Ken Buck is disgusting and is a disservice to people of Colorado,” said Buck spokesman Owen Loftus. “When it comes to women and men, they’re worried about jobs. . . . That’s what everyone cares about. Voters understand this is a machine set up to smear Ken Buck, and they aren’t buying it.”

The story, pushed out by ProgressNow and the Democratic Senatorial Campaign Committee, is the latest effort to tar Buck as insensitive to female voters, political observers say.

Last month, ProgressNow held a news conference with rape victims decrying Buck’s abortion views — he supports it only when the mother’s life is in danger.

And the campaign of his Democratic opponent, Sen. Michael Bennet, has hammered on that stance in ads as it works to draw in female voters.

A recent SurveyUSA poll conducted for The Denver Post found Buck lags behind Bennet among women by 8 percentage points, but Bennet trails Buck among men by 12 percentage points.

“Michael Bennet and ProgressNow continue to work that gender gap, but at some point the Dems have to turn their strategy to close the margin among men,” said Eric Sondermann, a Denver-based political strategist. “There’s no way Michael Bennet can lose men by 15 points and pull this thing out.”

A transcript of the woman’s tape was released Monday on the left-leaning Colorado Independent website. The audio was released Tuesday on the Huffington Post.

Kjersten Forseth, executive director of ProgressNow, said Tuesday that she resented the Buck campaign’s allegation she was politicizing the sexual-assault story.

“I was shopping around the ‘buyer’s remorse’ quote. That’s what mattered to me,” she said. “It’s a 5-year-old story. It’s not new. It’s a case that’s been out there the whole time. The victim decided to speak out last week when she was asked, and that is the story.

“. . . He grilled this victim, rather than helping her build a case … then said publicly that it ‘was a case of buyer’s remorse,’ Forseth said. “It is heartless.”

Loftus said after Buck’s conversation with the victim, he took the case to the Boulder County district attorney’s office for a second opinion because that office prosecutes a large number of date-rape cases every year.

That office agreed with Buck’s decision, Loftus said.

The strategy to go after Buck’s past decisions — however fair — can work to change voters’ minds, said Lori Weigel, a Republican pollster in Golden.

“They’re trying to establish more of a character trait, rather than litigate the facts in a particular case,” she said. “People vote on, is someone a leader? Do I think they share my values? And do I think they’re going to have my interests at heart? After a while, some of the messages up on TV are going to burn in.”

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